Electron beam devices, in particular a scanning electron microscope (hereinafter also referred to SEM) and/or a transmission electron microscope (hereinafter also referred to as TEM) are used for examining objects (samples) to obtain information about the properties and behavior of these objects under certain conditions.
In the case of an SEM, an electron beam (hereinafter also referred to as a primary electron beam) is generated by a beam generator and focused by a beam guidance system on an object to be examined. The primary electron beam is guided in a grid pattern by a deflecting device over a surface of the object to be examined. The electrons of the primary electron beam then interact with the material of the object to be examined. As a result of this interaction, in particular electrons are emitted from the surface of the object to be examined (so-called secondary electrons) and electrons of the primary electron beam are backscattered (so-called backscattered electrons). The secondary electrons and backscattered electrons are detected and used for image generation. This yields an image of the surface of the object to be examined.
In the case of a TEM, a primary electron beam is also generated by a beam generator and focused by a beam guidance system on an object to be examined. The primary electron beam passes through the object to be examined. As the primary electron beam passes through the object to be examined, the electrons of the primary electron beam interact with the material of the object to be examined. The electrons passing through the object to be examined are imaged by a system including an objective lens and a projective lens on a luminescent screen or on a detector (for example, a camera). In addition, it is also possible to provide for detecting electrons backscattered on the object to be examined and/or secondary electrons emitted by the object to be examined by another detector to image an object to be examined. The imaging is performed in the scanning mode of a TEM. Such a TEM is usually referred to as a STEM.
The electrons passing through the object in a TEM are detected by a detector connected downstream from the object—starting from the beam generator toward the object along the optical axis of the TEM.
In a SEM, the secondary electrons or backscattered electrons are detected with a detector, for example, which is situated inside the objective lens or in an area between the objective lens and the beam generator. For example, a SEM having the features mentioned above is known, in which a first detector and a second detector are offset from one another along the optical axis of the SEM for detecting the secondary electrons and backscattered electrons. Both the first detector and the second detector have an aperture. The first detector situated in the vicinity of the object to be examined is used to detect the electrons which emerge from the object to be examined at a relatively large solid angle whereas the second detector which is situated in the area of the beam generator is used to detect the electrons emerging from the object to be examined at a relatively small solid angle. To arrive at the second detector, these electrons pass through the aperture of the first detector which is provided for the passage of the primary electron beam.
Furthermore, an SEM which also has the aforementioned features is also known from the prior art. This known SEM is also additionally provided with a first detector and with a second detector. The first detector and the second detector are offset from one another along an optical axis of the SEM. The first detector is provided with an adjustable aperture to mask out secondary electrons so they do not strike the first detector.
With regard to the prior art cited above, reference is made, for example, to DE 198 28 476 A1 and DE 103 01 579 A1, which are incorporated herein by reference.
A particle beam, for example an electron beam, guided onto an object, may also interact with the object (in addition to the interaction particles already mentioned above) in such a way that electromagnetic radiation occurs in the form of cathodoluminescence. By detecting and analyzing the cathodoluminescence (for example, by an intensity analysis and spectral analysis), properties of the material of the object may be determined, for example, the determination of recombination centers, lattice defects, impurities and phase formations. The preceding list is to be understood merely as an example and is not conclusive.
Electron beam devices using which cathodoluminescence is also analyzed are known from the prior art. For example, there is a known electron beam device using which an object situated in a sample chamber is bombarded with an electron beam. Due to an interaction of the electron beam with the material of the object, the object emits light due to cathodoluminescence (hereinafter also referred to as cathodoluminescent light). The cathodoluminescent light is guided to a detector by an ellipsoidal mirror through a window situated in a wall of the sample chamber. The detector is thus situated outside of the sample chamber. In the case of another known electron beam device, using which cathodoluminescence is also analyzed, an object situated in a sample chamber is also bombarded with an electron beam. The object emits cathodoluminescent light, which is guided via a waveguide out of the sample chamber and further to a detector.
In the known prior art, the cathodoluminescent light is therefore detected at a relatively great distance from the object emitting the cathodoluminescent light. This results in an inferior efficiency in detecting the cathodoluminescent light because the cathodoluminescent light is detected only in a very restricted solid angle with respect to the object. Thus a portion of the photons of the cathodoluminescent light is not detected by the detector. Furthermore, the path from the source of the emitted cathodoluminescent light (i.e., the object) to the detector is relatively long. Intensity losses occur due to this path alone, which has a negative effect on the signal detected by the detector overall. Furthermore, intensity losses also occur in the waveguides used. In the known prior art, multiple waveguide elements linked together are also used, so intensity losses may also occur at a coupling point between two different waveguide elements.
Using waveguides and the ellipsoidal mirror also has another disadvantage. Because of the waveguides or the ellipsoidal mirror used, a portion of the secondary electrons or backscattered electrons is obscured, so that they are no longer able to strike a detector. This results in poor imaging.
Another disadvantage of the known electron beam devices in which the cathodoluminescent light is analyzed is that each detector used in these electron beam devices is essentially designed to detect only interaction particles or to detect only electromagnetic radiation. Therefore, in the case of the known electron beam devices, multiple detectors are always provided to be able to detect both interaction particles and electromagnetic radiation. This results in a greater complexity with regard to construction and assembly of these electron beam devices because vacuum feed-throughs and control units must be provided for each detector.
With regard to the prior art cited above, reference is made to DE 197 31 226 A1, EP 0 914 669 B1 and GB 1 369 314, which are incorporated herein by reference.
Accordingly, it would be desirable to provide a detection device and a particle beam device having a detection device, using which good efficiency in detecting interaction particles and electromagnetic radiation is ensured.